Pressure and Flow Testing Tool

How to Use This Tool

Setup

1. When you receive this tool it should be assembled for you. If it is not, assemble it so it matches the picture above.
   
2. With the water turned off, connect your garden hose or hose spigot to the black fitting on the inlet (left) side of the picture. It should screw on easily, so just use your hand to tighten it. This process will be easiest if you use a garden hose, but you can connect it directly to your spigot in a pinch.
3. Attach a second garden hose to the white fitting on the outlet (right) side of the picture. This step is optional, but will make it easier to read the pressure during testing.
4. Get either a five-gallon bucket or an empty one gallon milk jug. We'll use this container to measure the flow rate (a technical term for the water output). You can find a five gallon bucket at a hardware or auto supply store if you don't have one.
5. Make sure you have a timer handy such as a phone or watch.
6. Ensure that the ball valve (on the right side of the picture) is closed. The valve is closed when the handle is perpendicular to the valve. For reference, the valve shown in the picture is in the open position. Note that the valve you receive may have a different color handle, but don't worry, that won't affect how it operates.

Testing

1. After you've done everything listed in the setup section, turn the water at your hose spigot on all the way. It's important that you turn it on all the way so you get an accurate reading of the pressure and flow rate. If you only open it partway then your reading will not reflect the pressure and flow rate provided when the spigot is open all the way.
2. Give it a few seconds, then record the pressure reading on the gauge. This reading is the static pressure, which is the pressure in the system when no water is coming out.
3. Position your bucket or milk jug so that you can fill it with the tool once you turn the ball valve (on the right side of the picture) to the open position. Make sure you have your timer ready, as you are going to time how long it takes to fill your container.
4. Once your container is positioned and your timer is ready, open the ball valve all the way and start your timer. You want to determine how long it takes to fill the container. Make sure to write this number down.
5. After you are done filling your container and timing it, leave the water running at full blast and record the pressure reading on the gauge. This is your minimum pressure. Pressure and flow rate have an inverse relationship, which means as one goes up, the other goes down. With your spigot running full-blast you have maximum flow rate, which means you also have minimum pressure
6. NOTE: If you want to measure only your flow rate, you don't even need to buy this item! Just open your spigot all the way and time how long it takes to fill a five gallon bucket or milk jug, then move on to the calculations step below to calculate your flow rate.
7. Bonus step: once you have installed your drip system, take the pressure regulator part of this tool (including both black fittings) and put it in your head assembly in place of your pressure regulator, then turn the system on. Let it run for a few seconds (so water can start coming out of your drippers) then record the pressure reading on the gauge. This is your dynamic pressure, which is the pressure in the system at the flow rate of the system. You can use this to troubleshoot your system, determine if you need a pressure regulator, or decide whether you have enough pressure to add more drippers or sprayers to your system.

Calculations

In this section we will describe how to calculate your flow rate given the information you gathered in the testing section. The examples directly below will assume 30 seconds to fill the given container.

1. First we need to determine our gallons per second (GPS). To find this, take the size of your container (in gallons) and divide it by the time it took to fill (in seconds). For example: if it took 30 seconds to fill a one gallon container, then you have 1 / 30 = .0333 gallons per second. If it took 30 seconds to fill a five gallon container, then you have 5 / 30 = .1667 gallons per second. It's okay to round the numbers!
2. Next, multiply that number by 60 to find gallons per minute (GPM). For our above examples, that comes to .0333 x 60 = 2 GPM for the milk jug and 10 GPM for the five gallon bucket. 
3. Flow rate for drip systems are typically measured in gallons per hour (GPH), so we'll multiply those numbers by 60 one more time to find gallons per hour: 2 x 60 = 120 GPH for the milk jug and 10 x 60 = 600 GPH for the five gallon bucket
4. Note that the examples mention both a milk jug and a five gallon bucket, but you only need to use one while testing. If you do use both, once you've done the calculations, you should see that they flow rate result is the same for both.

Real World Examples

You have a five gallon bucket and you time it at 23 seconds to fill with your spigot all the way open.

1. 5 gallons / 23 seconds to fill = .217 gallons per second
2. .217 GPS x 60 seconds per minute = 13.02 gallons per minute
3. 13.02 GPM x 60 minutes per hour = 781.2 gallons per hour
4. In practical drip irrigation terms, this means you could supply 781x 1 GPH emitters with this spigot before you run out of water.

You have a one gallon milk jug and you time it at 46 seconds to fill with your spigot all the way open.

1. 1 gallon / 46 seconds to fill = .021 gallons per second
2. .021 GPS x 60 seconds per minute = 1.26 gallons per minute
3. 1.26 GPM x 60 minutes per hour = 75.6 gallons per hour
4. In practical drip irrigation terms, this means you could supply 75x 1 GPH emitters with this spigot before you run out of water